1. Field of the Invention
The present invention relates to an ink tank preferably used for an ink-jet recorder or the like, particularly to a liquid supply method in which a part of a container can be changed.
2. Related Background Art
A conventional ink-jet recorder uses an ink tank for storing ink by a negative pressure generated by a capillary force as an ink tank for storing a liquid (ink) to be attached to a recording medium to perform recording and supplying the ink to an ink-jet recording head for discharging the ink to the recording medium.
The most general configuration of the ink tank uses the capillary force of a porous body and includes a porous body such as sponge set or preferably compressively set in the whole ink tank to store ink and an atmospheric air communication portion capable of introducing air into an ink storage portion for smoothly supplying ink under printing.
However, the ink tank using the porous member as a capillary force generating member for storing ink has a low ink-storage efficiency for unit volume. Therefore, the present applicant proposes an ink tank comprising a capillary force generating member container for storing a capillary-force generation member and a liquid supply container for storing the ink to be supplied to the capillary force generating member container though a communication portion in Japanese Patent Application Laid-Open No. 7-125232. That is, in case of the above configuration, because the liquid supply container stores only ink, the ink storage efficiency is improved by storing ink in the container.
The liquid supply container is substantially closed except the communication portion and the capillary force generating member container is exposed to the atmospheric air through the atmospheric air communication portion. When ink is supplied from the liquid supply portion, air is introduced into the capillary-force generation member from the atmospheric air communication portion through a buffer chamber and the ink is supplied to the capillary-force generation portion from the liquid supply container while the air is introduced into the liquid supply container from the capillary-force generation member. Ink is supplied to the capillary force generating member container from the liquid supply container in accordance with gas-liquid change operation.
Moreover, the present applicant proposes an invention making it possible to change liquid containers of an ink tank having the above structure in Japanese Patent Application Laid-Open No. 6-226990. According to the invention, it is possible to repeatedly use a capillary force generating member container by consuming the ink in the liquid supply container and thereafter, changing the empty liquid supply container to a new liquid supply container filled with ink.
On the other hand, the present applicant proposes an ink tank using a fiber body made of a thermoplastic olefin-based resin (e.g. polypropylene or polyethylene) as a capillary-force generation member of the ink tank in Japanese Patent Application Laid-Open No. 8-20115. The ink tank is superior in ink storage stability and moreover superior in recycling characteristic since both the body of the ink tank and the fiber body are made of the same kind of material.
The present inventor et al. studied a liquid supply method using the above gas-liquid change system and resultantly obtained new information for flow and change of liquid and gas introduction about connection position and setting/removal between a liquid supply container and a negative pressure generating member container.
That is, the present inventor et al. completed a new liquid supply method by setting a plurality of liquid storage members (sponges or fiber bodies or the like serving as negative pressure generating members) in a negative pressure generating member container, noticing the positional relation between their contact faces of the storage members and joints of a liquid supply container with the members, and technically analyzing a configuration or system for further improving a liquid supply performance.
A liquid supply method according to the present invention is a liquid supply method according to a liquid supply system comprising a liquid supply container having a liquid storage portion for storing liquid in a closed, a capillary-force generation member which can be set to or removed from the liquid supply container and hold the liquid, an atmospheric air communication portion for communicating with atmospheric air, and a capillary force generating member container provided with a liquid supply portion for supplying liquid to the outside, which is applied to a system using at least two liquid storage members made of fiber and contacted each other as the capillary force generating member.
As a result of studying the above liquid supply system, the present inventor et al. obtained the following three aspects.
(First aspect)
It is a first aspect according to the present invention that at the time of taking a liquid supply container out of a capillary force generating member container, movement of the ink left in a communication portion to a capillary force generating member is changed due to the relation between the position of a contact face of the liquid storage member and the position of the communication portion.
In this first aspect, it is characterized that the contact face is present below the upper end of the communication portion.
(Second aspect)
It is a second aspect according to the present invention that movement of gas during gas-liquid change operation is changed due to the relation between the position of a contact face and that of a communication portion.
In this second aspect, it is characterized that the contact face is present below the upper end of the communication portion and above the lower end of the communication portion.
Even if a gas-liquid interface lowers as ink is consumed and the level of ink in a liquid supply container lowers, lowering of the gas-liquid interface is controlled by the contact face in the communication portion. Therefore, air is introduced into a liquid supply container from the upper side of the communication portion before it is introduced into a lower absorption body (liquid storage member) and thereby, the ink discharged out of the liquid supply container is directly discharged to the lower absorption body (liquid storage member).
Therefore, it is possible to sequence operations and make the operations securely function so as to first, consume the ink in the upper absorption body and the ink in the liquid supply container through gas-liquid change operation and thereafter consume the ink in the lower absorption body (liquid storage member).
(Third aspect)
It is a third aspect according to the present invention that ink movement in a capillary force generating member container when connected with a liquid supply container is changed due to the relation between the position of a contact face and that of a communication portion.
In this third aspect, it is characterized that the contact face is present below the lower end of the communication portion.
When the liquid supply container is connected to the capillary force generating member container in which ink is consumed and the ink is injected into the liquid supply container, the injected ink controls a gas-liquid interface once by a pressure-welding face because the contact face is formed at the lower side of the communication portion. Therefore, it is possible to immediately stabilize the gas-liquid interface of the injected ink.
The present invention is summarized by an invention of xe2x80x9clocating a contact face below the upper end of a communication portionxe2x80x9d as the synthesis of these first to third aspects.
Under the normal operating state in which a liquid supply container is connected with a capillary force generating member container, a gas-liquid interface L is formed nearby the upper end of a communication portion. Therefore, in case of a liquid supply method of the present invention, a gas-liquid interface is formed in the upper capillary force generating member in two liquid holding members contacted each other under the normal operating state. Therefore, the liquid (ink) left in the communication portion at the time of taking the liquid supply container out of the capillary force generating member container is absorbed in the capillary force generating member container as the gas-liquid interface rises in the upper capillary force generating member. Thus, the ink left in the communication portion can be smoothly absorbed because it can be avoided that a gas-liquid interface reaches the contact face between two liquid holding members due to absorption of ink and an ink absorption rate is decreased because the gas-liquid interface is not easily moved above the contact face like the case of the conventional example. Moreover, when setting the position of the contact face below the upper end of the communication portion and above the lower end of the communication portion, it is possible to prevent the gas-liquid interface from moving to the lower liquid holding member and consume the ink in the upper liquid holding member and thereafter, consume the ink in the lower liquid holding member by introducing an air into the liquid supply container. Furthermore, when connecting the liquid supply container to the capillary force generating member container in which ink is consumed and injecting ink into the container, because the contact face is formed at the lower side of the communication portion, the injected ink controls the gas-liquid interface once by the pressure welding face and thereby, it is possible to immediately stabilize the gas-liquid interface of the injected ink.
Moreover, by forming a configuration so that the contact face is present below the lower end of the communication portion, a gas-liquid interface can be more securely formed above the contact face between two capillary force generating members and the above action can be securely obtained. That is, even if ink is consumed and the gas-liquid interface lowers as the level of the ink in the liquid supply container lowers, the gas-liquid interface may not easily lower below the lower end of the communication portion as long as ink remains. Therefore, the gas-liquid interface may not easily move below the contact face between two liquid holding members.
A liquid supply method of the present invention makes it possible that the ink in an upper-side liquid holding member smoothly moves into a lower-side liquid holding member as the ink in a lower-side liquid holding member is consumed when the ink is consumed from a state in which the ink is held by two liquid holding members by using a configuration in which the dynamic resistance of the liquid in the liquid holding member upper than a contact face is smaller than the dynamic resistance of the liquid in the liquid holding member lower than the contact face and thereby, it is possible to control that a gas-liquid interface deforms and moves below the contact face between two liquid holding member.
Moreover, the above configuration makes it possible to smoothly absorb ink because the ink left in a communication portion when removing a liquid supply container from a capillary force generating member container contacts with an upper liquid holding member having a small dynamic resistance. Furthermore, by using a configuration in which the contact face between two liquid holding members is present below the lower end of a communication portion as described above, only an upper liquid holding member contacts with the opening face of the communication portion. Therefore, the ink left in the communication portion can be smoothly absorbed because the ink securely contacts with an upper liquid holding member.
Furthermore, by using a configuration in which the capillary force of a liquid holding member upper than a contact face is smaller than that of a liquid holding member lower than the contact face, ink can be effectively supplied to the lower liquid holding member from the upper liquid holding member before the ink held by the liquid member upper than the contact face is completely consumed. Therefore, it is possible to realize a configuration in which ink shortage does not easily occur.
By using a configuration in which the fiber density of a liquid holding member upper than a contact face is lower than that of a liquid holding member lower than the contact face, it is possible to realize a configuration in which a liquid holding member upper than a contact face has a smaller dynamic resistance of the ink in a member and a smaller capillary force.
Moreover, by using a fiber member in which main fiber directions are oriented to the same direction as a capillary force generating member, the ink moving in the member has a large dynamic resistance in a direction perpendicular to the fibers because the fibers interrupt movement of the ink but it has a small dynamic resistance in the direction parallel with the fibers. Therefore, by setting main fiber directions of a liquid holding member to an almost-horizontal direction in the operating attitude of the fibers, it is possible to stabilize a gas-liquid interface on a horizontal plane and prevent ink shortage from occurring because the gas-liquid interface deforms and a part of the interface reaches a liquid supply portion. By setting a layer in which directions of fibers are oriented to the same direction at least nearby the upper end of a communication portion on which a gas-liquid interface is formed under the normal operating state, it is possible to achieve the above effect.
Moreover, by bringing a liquid holding member having a capillary force larger than that of other liquid holding portion into contact with a liquid supply portion, it is possible to effectively introduce ink to the liquid supply portion and efficiently completely consume the ink.
Furthermore, by setting main fiber directions of the liquid holding member of the liquid supply portion to the direction parallel with an ink supply direction, it is possible to efficiently supply ink because the ink in the ink supply direction has a small dynamic resistance.
Furthermore, when a communication portion and a liquid supply portion are located at the same height, some of the ink moving from a communication portion up to a liquid supply portion in a capillary force generating member is introduced into the liquid supply portion after temporarily moving upward when a gas-liquid interface is raised due to an environmental change and may pass through a path longer than the path of the ink linearly moving from the communication portion up to the liquid supply portion. Thus, when there is a difference between lengths of ink paths, fluctuation occurs in components of inks supplied from the liquid supply portion after passing through paths different from each other in length. Therefore, by setting the communication portion above the liquid supply portion, the ink moving from the communication portion to the liquid supply portion passes through a comparatively long downward path and the length of an ink path is almost determined by the length of the downward path. Therefore, it is possible to control the fluctuation in lengths of ink paths and reduce the fluctuation in components of inks supplied from a liquid supply portion.